The present invention relates to controlled motion mechanical members used as a mechanical manipulator and, more particularly, to a motion controllable, anthropomorphic mechanical manipulator providing some of the capabilities of a human arm.
A strong desire for increased automation in the work place, and a need for remotely operable mechanical actuators, along with an increased ability to control such mechanical manipulators, has lead to substantial efforts in the development of robotics. As a result, substantial advances have occurred in many aspects of robotics.
One aspect permeating robotics is the controlling of mechanical manipulators, the portion of a robot used to change the position or orientation of selected objects. Ultimately, such manipulators are desired to have capabilities similar to those of a human arm, wrist and hand, or portions thereof.
Providing a mechanical manipulator simulating a human arm presents a difficult design problem. The human shoulder and the human wrist each can be considered to have three degrees of freedom in motion possibilities available to it, and the elbow can be considered to have a single degree of freedom in its possible motion. A number of mechanical joints for mechanical manipulators have been proposed which attempt to exhibit three degrees of freedom, and some of these have actually achieved such a capability. Such a joint typically has a base upon which one side of the joint is fastened, and from which a force imparting arrangement is provided to operate movable members in this fastened portion of the joint. Mechanical transmission arrangements then couple this motion on this fastened side of the joint to the controlled side of the joint to cause that portion to correspondingly move. Mechanical transmission arrangements so operating the controlled side of the joint have been of many kinds, including gears.
However, such joints have often been constructed using a substantial number of parts causing significant expense, and with the result that they are often difficult to assemble. Further, such joints often fail to have the controlled portion thereof exhibit the desired dexterity and range of motion. In addition, the "stiffness" of such joints, i.e. their ability to have the controlled portion hold a particular position with little displacement therefrom despite substantial forces occurring on the output end of this controlled portion, is often seriously deficient. Thus, there is desired a joint overcoming such deficiencies so that an arm-like mechanical manipulator can be provided with motion possibilities substantially equivalent to that of a human arm, and to have the controlled portion thereof be maintainable in a selected position despite substantial forces occurring thereon.